Oscillation generator



Oct. 17, 1933. v. K. ZWORYKIN OSCILLATION GENERATOR- Filed April 12, 1927 2 Sheets-Sheet 1 l N VE NTO R V/ad/m/r K Zwar /(m.

ATTCSRNEY Patented Oct. 17, 1933 UNITED STATES PATENT OFFICE OSCILLATION GENERATQR Application April 12, 1927. Serial No. 183,225

28 Claims.

My invention relates to electron tubes and particularly to those intended to generate or amplify electrical oscillations at frequencies of the order of 10,000 kilocycles or more per second.

One of the objects of my invention is to produce a generator of very high frequencies.

Another object of my invention is to keep highfrequency currents out of the supply leads to the electrodes of a three-electrode tube without re- 19 sorting to the use of choke coils.

Another object of my invention is to produce an oscillation generator of unusually constant frequency.

Another object of my invention is to reduce the 5 physical dimensions of a short-wave-oscillation generating apparatus.

Another object of my invention is to reduce losses in a short-wave generating apparatus, particularly those due to stray capacity and leakage 9 over insulators in the circuit connections.

Other objects of my invention will be apparent upon reading the following description.

An efficient generator of the very high frequencies above-mentioned is to be desired by reason of the many advantages known to be inherent in transmission at shorter wave-lengths than are now usual.

Many radio broadcasting stations now operate at a frequency of the order of 1,000 kilocycles per second. Experiments have shown, however, that many difficulties found with such transmitting stations are eliminated if higher broadcasting frequencies are employed. This is notably true in the case of so-called fading. With higher broadcast frequencies, unusual possibilities arise in directive radio transmission. The entire trend of the radio art at present is in the direction of much higher frequencies than those last named.

In attempting to produce generators for such high frequencies, however, many dimculties have been found. The leads between external COldensers and inductances have such a large stray capacity that they seriously limit the magnitude of the frequency which can be obtained if generating tubes of the ordinary type are employed.

Furthermore, even where it is possible to sumciently reduce stray capacity efiects, difiiculties have been encountered because of the high gridcharging current that must traverse the inleading wire to the grids of generating tubes for very high frequencies. Also, the capacity eifect of surrounding objects is a very considerable part of the total capacity in the grid and plate circuits of such tubes and, accordingly, the frequency of such tubes is very sensitive to movement of persons or objects in the vicinity of the generator. Con stancy of frequency is, therefore, difiicult to attain.

The high-frequency electric fields which surround all of the conductors to such generating so tubes have a tendency to cause considerable losses in the glass walls of the tube, particularly is this true of the concentrated fields present where inleading wires traversed by high frequency currents pass through the tube walls. as Losses in all kinds of electrical insulators increase rapidly with the frequency. Moreover, at such high frequencies the grid charging current is large and requires inleading conductors of considerabl size, the sealing of which is not easy. 7a

A tube in which the necessary inductances and capacities to constitute the oscillating circuits are included within the tube itself avoids all of the foregoing difiiculties. Since the high-fre-= quency currents are confined to the interior of the '5 tube itself, there is no grid lead to accumulate static charges. There are no external leads to produce stray electrostatic fields or capacities and, since the conductors sealed through the tube walls do not carry high-frequency current, the gr greater part of the above-mentioned dielectric losses are eliminated. Moreover, since the ca= pacity and inductance values are small, a very compact transmitting set is realized by their enclosure within the walls of the transmitting tube. 35

With the foregoing objects and features in mind, my invention comprises the methods and constructions described in the following descrip= tion and illustrated in the drawings, wherein Figure 1 is a vertical sectional view of a tube adapted to act as a generator of high-frequency oscillations Fig. 2 is a sectional view on the line H-H of Fig. i;

Fig. 3 is a diagrammatic view of the equivalent 95 connections of the tube shown in Fig. 1;

Fig. i is a vertical sectional view of a tube adapted to act as a high-frequency amplifier; and

Fig. 5 is a diagrammatic view of the equivalent loo circuit connections or" the tube shown in Fig. 4.

Referring to Fig: l, a vacuum-tight glass con tainer 1 has, at its base, the usual reentrant press 2 through which are sealed inleading wires 3 for an electron-emissive cathode 4 of a conventional type. The press 2 has two pairs of arms 5 and 6 projecting from it. Each of the arms 5 supports one member of a pair of semi-cylindrical grids 7 which are concentric with the cathode 4. Each of the arms 6 supports one member of a pair of semi-cylindrical plate electrodes 8 concentric with the filament 4 and the grids 7. The wires 9 supporting the main electrodes 8 are interconnected through a helix 10 positioned well above the cathode, grid and main electrodes 4, '7 and 8, aforesaid. A lead 11, sealed through the top of the tube 1, is connected to substantially the midpoint of the helix 10. Each of the anode members 8 supports a member 12 in the form of a split ring, lining the interior wall of the tube near the level of said anode.

The two split rings 12 are spaced apart in an axial direction, and around the outside of the tube is a split ring 13 adapted to overlap that portion of the tube wall adjacent to the split rings 12. The set of rings 12 and 13, accordingly, form a condenser of which the glass wall of the tube is the dielectric. By moving the ring 13 upward and downward along the tube, the capacity of the condenser varies.

At one end of each half of the grids '7, wings 14 project radially outward, the wing on one semi-cylinder being diametrically opposite to the wing on the other semi-cylinder. Each plate member 8 has, similarly, a wing 15 projecting radially outward at one end. The wing 15 belonging to each anode semi-cylinder is disposed parallel to the wing 14 of that half of the grid which is interposed between the cathode and the other anode semi-cylinder. Fig. 2 shows this construction. The dimensions and spacing of tlne members 14 and 15 are so related to those of the members 7 and 8 that the electrostatic capacity between each semi-cylindrical anode and the semi-cylindrical control grid adjacent thereto is small, compared with the electrostatic capacity between the wing member 15 belonging to the same anode and the wing member 14 belonging to the opposite semi-cylinder of the grid. The diagram in Fig. 3 illustrates these electrical relationships by showing 'the condensers 16 interconnecting each anode plate with the grid controlling current flowing between the cathode and the opposing anode.

A tube constructed in accordance with the foregoing description is connected to external electrical circuits in which the cathode is energized from the ordinary source 1'7 through a control resistor 18, and a source of electromotive force 19 is connected between the cathode and the lead 11 which taps the helix 10 at its midpoint. The ring members 12 and 13 together constitute a variable condenser connected between the anodes; this is represented diagrammatically by the condenser 20 in Fig. 3. Because of the capacity coupling 16 between each grid '7, and the opposing anode 8, the tube, when supplied from the source or electromotive force 19 will act as a generator of oscillations, the frequency of which is determined by the magnitude of the inductance 10 and the variable condenser 20. The high-frequency current flowing through the inductance 10 will act inductively upon a helix 21 external to the tube which may be used to supply high-frequency current to any desired load circuit.

Since the high-frequency currents are confined to the grid '7, anodes 8, helix 10 and variable condenser plates 12 and 13, no high-frequency currents tend to flow in the external circuit 19, and the leads 3 and 11 are relieved of the duty of carrying such currents. Heating of the glass walls in the neighborhood of these leads is, therefore,

avoided. Furthermore, since the condenser plates 12 and 13 almost completely surround the anodes and grids of the tube, they act as an electrostatic shield for nearly the entire high-Irequency circuit. Stray capacity between parts of those highfrequency circuits and external objects is, therefore, practically nil.

Fig. 4 shows a tube designed to act as an amplifier having all of its high-frequency circuits contained within the tube. The envelope 1 has a reentrant stem 2 through which are sealed leads 3 supplying a cathode 4 in the axis of the tube. Two support arms 5, projecting from the stem 2, support the two semi-cylindrical portions of a grid 7 which is concentric with the cathode 4. The other support arms 6, projecting from stem 2, support the two semi-cylindrical anodes 8, also concentric with the cathode 4. Two plate members 8 are interconnected through a helix 10 positioned well above the cathode 4, grid '7 and anode 8 just described. A lead 11 passes through the upper end wall of the tube and is connected substantially to the midpoint of the helix 10.

Each of the anode members 8 supports a member in the form of a split ring 12 adjacent to the inner wall of the tube approximately at the level of said anodes. The ring members 12 are spaced apart, and the exterior wall of the tube is surrounded by a split ring 13 which is adapted to overlap the ring members 12. The split rings 12 and 13 combine to form a variable condenser connecting the two anode members 8.

Each of the grid members '7 has a wing 14 projecting from one of its ends in a radially outward direction, the two wings being diametrically opposite, each other. Each of the plate members 8 has a wing 15 projecting radially outward at one of its ends, the two being likewise diametrically opposite each other. The wing 14, attached to one grid semi-cylinder, is located parallel, and in close proximity, to the wing 15 attached to that anode semi-cylinder which is diametrically opposite to said grid member.

In all the above described arrangements, the amplifier tube of Fig. 4 is similar to the generator tube shown in Fig. 1.

Below the anode, grid and cathode members in Fig. 4 is located a helix 22 supported, at its midpoint on one of the cathode leads 3 and having its two ends connected respectively to the two semi-cylindrical grid members '7. The helix 22 may be made of a conductor having high resistance or may be otherwise arranged in any well known fashion to interpose a considerable resistance to current flowing through it from one grid member '7 to the other. The helix 22 is preferably positioned with its axis transverse to the axis of the tube 1. External to the tube 1 and coaxial with the helix 22 is a 0011 23 which may be supplied, from any desired source, with a current which it is intended to amplify. The inductive action of such current upon the helix 22 impresses between the cathode 4 andileach grid member '7 an alternating electromotive force which it is desired to amplify.

Fig. 5 shows these arrangements diagrammatically, the coil 23 inducing the aforesaid electromotive force in the winding 22 and thereby impressing it upon the grid members '7 through the resistances 24 above described.

By reason of the capacitative connection between the wings 14 and 15, symbolized by the small condensers 16 in Fig. 5, a source of electromotive force 19, connected between the cathode 4 and the lead 11, will cause the above described tube to act as a generator oi. oscillations of a frequency determined by the capacity of the variable condenser 20 constituted by the ring members 12 and 13 and symbolized at 20 in Fig. 5.

High-frequency currents will, therefore, continuously flow through the helix 10 and will induce a corresponding electromotive force in a helix 21 positioned external to the tube and in in ductive relation to helix 10. The winding 21 may be connected to any desired load circuit.

Any alternating current flowing through the winding 23 will, accordingly, impress its electromotive force upon the grids 7 and thereby vary the amount of current flowing between the anodes 8 and the cathode 4. Consequently, the current flowing through the helix 10 and variable condenser 20 will vary in turn, and the electromotive force supplied to the load circuit by the winding 21 will vary in a multiple proportion to the current variations in winding 23. By properly adjusting the frequency of the oscillations locally generated in the circuit comprising helix 10 and condenser 20 so that it will produce beats with the oscillations induced by supply circuit 23, the tube of Fig. 4 may act as a heterodyne radio receiver.

It will be seen that tubes made in accordance with the foregoing construction confine the highfrequency currents to circuits entirely enclosed within the glass envelope; that the number of inleading wires passing through the envelope are correspondingly decreased; dielectric losses in the glass are minimized; stray capacities between connections of condensers and inductances are eliminated; effects of external capacities are practically made negligible by the internal shielding inherent in the construction; difliculties and losses arising from the necessity of insulating external leads are eliminated; and a compact operating arrangement secured.

While I have illustrated my invention in the structures above described, it will be obvious that many modifications thereof can be made without departing from the general principles embodied therein. Accordingly, I desire that the language of the appended claims shall be construed to cover the broad principles of the invention, as well as its specific embodiment therein shown, and that the claims shall be limited only by their explicit statements or in accordance with invention existing in the prior art.

I claim as my invention:

1. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a plurality of main electrodes, 2. control electrode for each main electrode, and means inside said container producing a capacitative coupling between each main electrode and its control electrode of lesser amount than that between said control electrode and another main electrode.

2. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a plurality of main electrodes, a control electrode for each main electrode, means inside said container producing a capacitative coupling between each main electrode and its control electrode of lesser amount than that between said control electrode and another main electrode, an inductance interconnecting said main electrodes, and means for connecting a source of electromotive force between a point on said inductance and said cathode.

3. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a plurality of main electrodes, a control electrode for each main electrode, means producing a capacitative coupling between each main electrode and its control electrode of lesser amount than that between said control electrode and another main electrode, and an inductance within said container interconnecting said main electrodes.

4. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a plurality of main electrodes, a control electrode for each main electrode, means producing a capacitative coupling between each main electrode and its control electrode of lesser amount than that between said control electrode and another main electrode, an inductance within said container interconnecting said main electrodes and a variable condenser in shunt to said inductance.

5. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a plurality of main electrodes, a control electrode for each main electrode, means producing a capacitative coupling between each main electrode and its control electrode of lesser amount than that between said control electrode and another main electrode, an inductance within said container interconnecting said main electrodes, a variable condenser in shunt to said inductance and a winding in inductive relation to said inductance and adapted to be connected in a load circuit.

6. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a control electrode between said cathode and each anode, and means to make the capacitative coupling inside said container between each control electrode and and the opposite anode greater than that between said control electrode and its adjacent anode.

7. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a control electrode between said cathode and each anode, and means to make the capacitative coupling between each control electrode and the opposite anode greater than that between said control electrode and its adjacent anode, inductance within said container interconnecting said main electrodes and means for connecting a source of electromotive force between a point on said inductance and said anode.

8. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a control electrode between said cathode and each anode, means to make the capacitative coupling between each control electrode and the opposite anode greater than that between said control electrode and its adjacent anode, inductance interconnecting said anodes within said container, a plate member connected to each anode and spaced apart inside said container adjacent the wall thereof, and a plate member adjacent the outer wall of said container adapted to overlap both said interior plate members.

9. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a grid for each anode having a portion of its surface between said anode and the cathode and another portion of its surface in close proximity to the other anode but outside the space between the last named anode and the cathode.

10. An electron-discharge device comprising a. vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a grid for each anode having a portion of its surface between said anode and the cathode and another portion of its surface in close proximity to the other anode but outside the space between the last named anode and the cathode,- inductance connecting said anodes and means for connecting a source of electromotive force between a point of said inductance and said cathode.

11. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a grid for each anode having a portion of its surface between said anode and the cathode and another portion of its surface in close proximity to the other anode but outside the space between the last named anode and the cathode, and an inductance within said container interconnecting said anodes.

12. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a grid for each anode having a portion of its surface between said anode and the cathode and another portion of its surface in close proximity to the other anode but outside the space between the last named anode and the cathode, inductance within said container interconnecting said anodes and a tap for connecting external circuits at a point of said inductance.

13. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a control electrode between said cathode and each anode, means to make the capacitative coupling between each control electrode and the opposite anode greater than that between said control electrode and its adjacent anode, inductance within said container interconnecting said anodes, means for connecting a source of electromotive force between a point of said inductance and said cathode and a winding in inductive relation to said inductance and adapted to be connected in a load circuit.

14. An electron-discharge device comprising a vacuum-tight container, a cathode adapted. to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a grid for each anode having a portion of its surface between said anode and the cathode and another portion of its surface in close proximity to the other anode but outside the space between the last named anode and the cathode, inductance within said container connecting said anodes, means for connecting a source of electromotive force between a point of said inductance and said cathode and a winding in inductive relation to said inductance and adapted to be connected in a load circuit.

15. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a grid for each anode having a portion of its surface between said anode and the cathode and another portion of its surface in close proximity to the other anode but outside the space between the last named anode and the cathode, an inductance on opposite sides of said cathode, a grid for each anode having a portion of its surface between said anode and the cathode and another portion of its surface in close proximity to the other anode but outside the space between the last-named anode and the cathode, a plate member connected to each anode and spaced apart inside said container adjacent the wall thereof,

a plate member adjacent the outer wall of said container adapted to overlap both said interior platemembers, an inductance within said container interconnecting said anodes and a tap forconnecting external circuits at a point on said inductance.

17. A cylindrical vitreous vacuum-tight cons tainer having a pair of semi-cylindrical anodes concentric therewith, a. cathode adapted to emit electrons disposed inside said anodes, a grid electrode having a portion of its area disposed between said cathode and the interior face of one anode and another portion of its area disposed in close proximity to a face of the other anode, two conducting plate members connected respece tively to each anode member within said. container, a plate member outside said container adapted to overlap said interior plate members, a concentric helical inductance within said container, means for connecting a source of electromotive force between said cathode and a point on said inductance, and a winding external to said container in inductive relation to said inductance.

18. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a pair of anodes, said anodes being on opposite sides of said cathode, a grid for each anode having a portion of its surface between said anode and the cathode and another portion of its surface in close proximity to the other anode but outside the space between the last-named anode and the cathode, an inductance interconnecting said anodes within said container, a tap for connecting external circuits at a point on said inductance, means for connecting a source of electromotive force between said tap and said cathode, a winding in inductive relation to said inductance and adapted to be connected in a load circuit, and a coil within said container connected at its midpoint to said cathode and at each terminal to one of said grids, said anodeinductance and winding being in substantially non-inductive relation to said coil.

19. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a plurality of main electrodes, a control electrode for each main electrode, an inductance within said container having its midpoint connected to said cathode and its terminals connected to each control electrode, a winding external to said container in inductive relation to said inductance, a second inductance within said container interconnecting said main electrodes, means for connecting a source of electromotive force between said cathode and a point on said second inductance and a winding external to said tube in inductive relation to said second inductance.

20. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a plurality of main electrodes, a

control electrode for each main electrode, means whereby the capacitative coupling between each main electrode and its control electrode is less than that between said control electrode and another main. electrode, inductance interconnecting said main electrodes, means for connecting a source of electromotive force between a point on said inductance and said cathode, and means to induce an electromotive force between at least one of said control electrodes and the cathode.

21. An electron-discharge device comprising a vacuum-tight container, a cathode adapted to emit electrons, a plurality of main electrodes, a control electrode for each main electrode, means whereby the capacitative coupling between each main electrode and its control electrode is less than that between said control electrode and another main electrode, inductance interconnecting said main electrodes, and inductances connecting each control-electrode with the cathode.

22. An electron-discharge device having a vacuum-tight container, an anode, a cathode, and a control electrode connected to a winding within said container, said Winding being connected to said cathode within said container, in combination with a winding external to said container in inductive relation to the winding first-mentioned.

23. An electron-discharge device having a vacuum-tight container, an anode, a cathode, and a control electrode, a winding within said container, a conductor connecting one terminal of said winding to said cathode at a point within said container, and a second conductor connecting the other terminal of said winding to said control electrode, said conductors being located entirely within said container.

VLADIMIR K. ZWORYKIN. 

